Brush holder for electric motors



y 1957 A. w. SEYFRIED 2,798,176

BRUSH HOLDER'FOR ELECTRIC MOTORS Filed Dec. 7, 1954 I INVENTOR. v ARTHURW. SEYFR/ED BY 7 fl i.

ATTORNEY Bnusn nornnn non ELECTRIC Morons Arthur W. Seyfried, Racine,Wis., assignmto Scovill Manufacturing Company, Waterbury, Conn, acorporation of Connecticut Application December 7, 1954, Serial No.473,646

Claims. (Ci. lilo- 247) This invention relates to brush holders forelectric motors.

The main object of the invention is to produce an improved brush holder,efficient for its intended purposes, in which a carbon brush and leadconnection are protectively mounted, comprising parts which areassembled without the aid of molding and broaching operations heretoforeemployed in producing prior art constructions.

it has been customary to mount the brush in a shaped brass tube moldedinto a phenolic plastic insulating member. A breaching operation on theinside of the tube was required to size it to fit with a minimum ofclearance on the core pins of the plastic mould in order to preventexcessive plastic flowing in between the core and brass tube. A secondbroaching operation was required after the insulating member had beenmolded on the tube to remove plastic material from the inside of thetube, and a brushing operation was needed to remove plastic on theoutside of the brass tube. An exposed end stamping and lead connectionwas attached at the outer end of the holder, which required the drillingand tapping of a hole in the plastic member. To protect the exposed endstamping and lead connection, an additional insulating cover was used toavoid exposure of live parts.

The brush holder embodying my invention consists of a brass tube, aterminal connection and two phenolic plastic insulator members, whichare separabiy assembled and mounted in assembled relationship in a motorhousing by means of a single clamp, without any molding, broaching orbrushing operations.

The brush holder herein shown and described obviates the costly and timeconsuming operations attending the molding of the tube into the plasticinsulator heretofore employed.

An important feature of the invention is the provision of cooperatingmeans on the tube and an insulator member whereby the tube isautomatically located and re tained in predetermined position merely byinserting the tube in the insulator.

Another feature is the provision of means in an insulator member forcovering all live parts of the assembly.

The construction herein shown and described is not only more efiicientthan prior art mechanisms, but can be produced at substantially lowercost.

These and other advantages will be apparent from the followingspecification.

In the drawings:

Fig. l is a side elevational view of a motor housing in which aremounted two brush holders embodying my invention.

Fig. 2 is a longitudinal vertical sectional view of a brush holderembodying my invention, on a scale larger than the holders shown in Fig.1, taken in the plane of the line 2-2 of Fig. 3.

Fig. 3 is an elevational view of the inner end of the brush holder.

ited States Patent Fig. 4 is a transverse sectional view in the plane ofthe line 44 of Fig. 2. v

Fig. 5 is a top plan view of the brass tube which is part of the holder.

Fig. 6 is a perspective view of a clamp by which the assembled holder ismounted on the motor housing.

In the preferred embodiment of my invention shown in the drawings, thebrush holder is indicated as a whole at 10. It comprises an open ended,formed brass tube 11 substantially rectangular in cross section buthaving side walls 12 partly concave on their inner surfaces as indicatedat 13. The top wall 14 of the tube is cut on the line 15 to form atongue 16 which is bent at 17 so that its free end extends upwardly fromsaid top wall of the tube for a purpose to be explained hereinafter. Thetube is designed to receive a carbon brush 18 to which is attached oneend of a coiled spring 19 and of a wire 20, which extends lengthwisethrough the spring, the other end of said wire being attached to a smallmetal disc 21 against which bears the free end of the compressed coiledspring 19. The cross sectional form of the tube 11 is such that thebrush has easy sliding movement longitudinally within the tube, and theconcave walls 13 accommodate the compressed coiled spring 19. The brush18, with attached spring 19, wire 20 and disc 21, is insertible as aunit in the tube 11.

The brush holder 11 also comprises two preformed, phenolic plasticinsulator members, an inner one 22 and outer one 23. The inner member 22consists of an open ended tubular body having a longitudinally extendingcentral bore complemental in shape to the exterior of the tube 11. Inits upper portion it is recessed as indicated at 24 to provide a shallowspace between the tube 11 and top of the member 22. The recess 24extends from the outer flanged end 25 of the insulator body to theshoulder 26 near the inner end of said insulator to accommodate thepunched up tongue on the tube 11. Preferably the recess 24 is deeper atits open end than at the end closed by the shoulder 26, to facilitatethe insertion of the tube 11 and tongue 16, as shown in Fig. 2. When theinner end of the tube 11, that is, the right hand end in Fig. 5, isinserted into the flanged end of the insulator 22, the tongue 16occupies the recess 24 and its free end abuts the shoulder 26 or closedend of the recess, serving thereby to locate the tube in the insulatorin predetermined position and also to exert pressure against the recessupper wall to frictionally retain the tube and insulator in theirassembled relationship.

The outer insulator member 23 has flattened side walls 27, and, like themember 22, is provided with a central bore shaped to receive the tube11. The flanged end 28 is adapted to abut the flanged end 25 of themember 22. The outer end of the insulator 23 is closed by a wall 29provided with a central opening 30 surrounded by the annulus 31.

A terminal connection, in the form of a U-shaped piece of metal 32, towhich is connected an insulated lead wire 33, is located in the closedend of the member 23, with the wire 33 extending outwardly through theopening 30, and the terminal connection bearing against the innersurface of the end wall 29.

A conventional motor housing 34 is provided with tubular extensions 35for receiving the brush holders 10, as shown in Fig. 1. An armature isindicated at 36. Before mounting the brush holders 10 in the motorhousing, the parts are assembled as shown in Fig. 2, by sliding theinner end portion of the tube 11 into the flanged end of the insulator22 with the tongue 16 in the recess 24. The terminal connection isinserted into the tube 11 with the insulated wire 33 extending outwardlythrough the opening 30 in the end wall 29 of the insulator 23, andsliding the insulator 23 over the outer end portion of the tube 11.

When the free end of the tongue 16 contacts the recess shoulder 26, theflanges 2S and 25 of the insulator members contact as shown in Figure 2,and the described parts are retained in separable assembled relationshipby frictional engagement between the tube and insulator members and thepressure exerted by the spring metal tongue 16 against the upper wall ofthe recess 24. Finally the brush unit, including the brush 18, spring20, wire 19 and disc 21, is inserted in the tube 11, with the disccontacting the terminal connector 32.

To install the brush holders and brushes as shown in Fig. 1, theassembled units are inserted from the outside of the motor housing 34into the tubular projections 35, the movement being limited by thecontacting of the insulator flange 25 with the edge of the housingprojection 35. Then a clamp 37, such as shown in Fig. 6, is attached bya screw 38 to the motor housing. The clamp 37 comprises an aperturedcross piece 39 and two offset vertical arms 40 terminating in inturn'edends 41. To apply the clamp to the brush holder 10, the arms 40 arepassed upwardly to straddle the insulator 23 and contact the flat sides27 thereof, and when the clamp has been fastened by the screw 38extending through the apertured cross piece 39 into the housing 34, theinturned ends 41 engage notches 42 in the exposed face of the flange 28of the insulator 23. This construction holds the brush holder assemblyfirmly in position in the motor housing and also prevents the holderassembly from turning. The brushes 18 yieldingly contact the armature36, and wear of the brushes is automatically compensated for by theexpansion of the compressed spring 20.

From the foregoing it will be apparent that the separately fabricatedparts which constitute the brush holder of my invention can be quicklyand easily assembled and are retained in their intended relationshipwithout additional operations or separate fastening means, and withoutresorting to molding, welding or the like. Further, the form andconstruction of the insulator members are such that all live parts ofthe brush assembly are protected and the connection to a source ofelectrical current can be made conveniently outside of the holder.

Changes may be made in details ofconstruction and in the form of partswithout departing from the scope of my invention as defined by theappended claims.

I claim:

1. A brush holder for electric motors comprising an open end tube, twoaxially aligned hollow insulator members, the tube having a sliding fitwithin said members, one of said insulator members being open ended,cooperating means on said open end insulator member and tube retainingthe tube in the insulator in separable predetermined relationship, anapertured end wall on the other of said insulator members, an insulatedwire extending loosely through said apertured end wall, and a terminalconnector attached to the wire and located in the tube adjacent saidinsulator end wall.

2. A brush holder for electric motors comprising an open end tube, twoaxially aligned hollow insulator members, the tube having a sliding fitwithin said members, one of said insulator members being open ended,coopcrating means on said open end insulator member and tube retainingthe tube in the insulator in separable predetermined relationship, saidmeans comprising a spring metal tongue projecting from the tube andengaging a wall of the insulator member, an apertured end wall on theother of said insulator members, an insulated wire extending looselythrough said apertured end Wall, and a terminal connector attached tothe wire and lo'catedin the tube adjacent said insulator end wall.

3. A brush holder for electric motors comprising an open end tube, twoaxially aligned hollow insulator'rnembers, the tube having a sliding fitwithin said members, one of said insulator members being open ended andhaving a central bore the walls of which are complemental to theexterior surfaces of the tube, a 'recessin one of saidwalls-communicating with saidcentral bore, the re- .4 cess being open atone end and closed at the other end, resilient means on the tube adaptedto project into said recess and to contact the closed end of the recess,an apertured end wall on the other of said insulator members, aninsulated wire extending loosely through said apertured end wall, and aterminal connector attached to the wire and located in the tube adjacentsaid insulator end wall.

4. In combination with a motor housing having a pair of tubularprojections at opposite sides of the housing, a brush holder insertiblein each of said tubular projections, said holder comprising an open endmetal tube, two axially aligned insulator members, the tube having asliding fit within said members, each of said insulator members having aradially projecting flange adjacent an open end abutting the otherflange, one of said flanges abutting the outer end of the tubularextension of the motor housing, cooperating means on the tube and one ofsaid insulator members retaining the tube in said insulator in separablepredetermined relationship, an apertured end wall on the other insulatormember, an insulated wire extending through said apertured end wall, aterminal connector attached to the wire and located in the tube adjacentsaid insulator end wall, and means engaging said other insulator memberand attached to the motor housing retaining said insulator members inflange abutting relationship on the tube.

5. In'combination with a motor housing having a pair of tubularprojections at opposite sides of the housing, a brush holder insertiblein each of said tubular projections, said 'holder comprising an open endmetal tube, two axially aligned insulator members, the tube having asliding fit within said members, each of said insulator members having aradially projecting flange adjacent an open end abutting the otherflange, one of said flanges abutting the outerend of the tubularextension of the motor housing, the other of said flanges having notchesin its outer face, cooperating means on the tube and one of saidinsulator members retaining the tube in said insulator in predeterminedrelationship, an apertured end wall on the other insulator member, aninsulated wire extending through said apertured end Wall, a terminalconnector attached to the wire and located in the tube adjacent saidinsulator end wall, a clamp engaging the notched flange of the otherinsulator member, and means attaching the clamp 'to the motor housingfor retaining said insulator members in flange abutting relationship onthe tube.

6. A brush and holder for electric motors comprising a brush unitconsisting of a brush, a coiled spring connected at one endto the brush,a wire connected at one end 'to the brush and extending through thecoiled spring, and a metal disc attached to the other end of the wireretaining the spring compressed between the brush and disc, and a holderfor the brush unit consisting of an open end tube, a pair of hollowaxially aligned insulator members, the tube having a sliding fit withinsaid members, one of said insulator members being open ended,cooperating means on said open end insulator member and tube retainingthe tube in the insulator in separable predetermined relationship, anapertured end wall on the other of said insulator members, an insulatedwire extending through said apertured end wall, and a terminal connectorattached to the wire and located in the tube adjacent said insulator endwall, the brush being slidably located in said tube and the disc of thebrush unit contacting with said terminal connector.

7. A brush holder for electric motors comprising an open end tube, twoaxially aligned hollow insulator members, the tube having a sliding fitwithin said members, one of said insulator members being open ended, andcooperating means on said open end insulator member and tube preventingrotation of the tube relatively to said member and including resilientmeans on the tube yieldingly engaging the insulator member and limitingits sliding movement relatively to the tube in one direction butpermitting withdrawal of the tube from said insulator member by slidingmovement in the opposite direction.

8. In combination With a fixed support, a brush holder for electricmotors comprising an open end tube, two axially aligned hollow insulatormembers, the tube having a sliding fit within said members, one of saidinsulator members being open ended and the other having opposite flatsides and a closed end, cooperating means on said open end insulatormember and tube preventing rotation of the tube relatively to saidmember and including resilient means on the tube yieldingly engaging theinsulator member and limiting its sliding movement relatively to thetube in one direction but permitting withdrawal of the tube from saidinsulator member by sliding movement in the opposite direction, a clamphaving spaced apart arms adapted to engage the fiat sides of said closedend insulator member and means for attaching the clamp to the fixedsupport.

9. The brush holder defined by claim 3, in which the recess in the openended insulator member is deeper at its open end than at its closed end.

10. The brush and holder defined by claim 6, in which the cooperatingmeans on said open end insulator member and tube includes resilientmeans on the tube yieldingly engaging the insulator member and limitingits sliding movement relatively to the tube in one direction butpermitting withdrawal of the tube from said insulator 10 member bysliding movement in the opposite direction.

References Cited in the file of this patent UNITED STATES PATENTS 152,449,764 Bluemink Sept. 21, 1948 FOREIGN PATENTS 51,706 Switzerland May14, 1910 197,501 Great Britain May 17, 1923

